Spinning solution of sulfochlorinated ethylene-propylene copolymer, filaments thereof, and process for obtaining them



Feb. 26, 1963 E'. m GIULIO ETAL 3,0 8

SPINNING SOLUTION OF SULFOCHLORINATED ETHYLENE-PROPYLENE COPQLYMER, FILAMENTS THEREOF, AND PROCESS FOR OBTAINING THEM Filed Nov. 3. 1958 INVENTORS ENZO 0/ G/UL/O FRANCESCO DENT BY Jo 5mm i n Emin/ ATTORNEYS 3,079,218 SPWNING St'PLUTlON OF SULFGCHLORINATED ETHYLENEPRQFYLENE CGEGLYMER, FHLA- MENTS THEREQF, AND PROCESS FGR OBTAIN- ENG THEM Enzo di Giulio, Ferraro, Htaly, and Francesco Denti, De-

catur, Alan, assignors to Montecatini Societal Generals per llndustria Mineraria e Chimica, Milan, Italy Filed Nov. 3, 1953, Ser. No. 771,185 Claims priority, application Italy Nov. 6, 1957 16 Claims. (Cl. 18--54) This invention relates to elastic yarns. More particularly, the invention relates to elastic yarns derived from ethylene-propylene copolymers and to methods for producing the filaments and yarns.

Ethylene-propylene copolymers containing from 30% to 70% by Weight ethylene in the copolymer molecule have been disclosed in the British Patent No. 856,736. The amorphous ethylene-propylene copolymers obtained by the process described in said patent are essentially free of homopolymers, show in the infra-red spectrum therefor bands between 13.4 microns and 13.8 microns, and have a molecular weight above 20,000. British Patent No. 861,542 discloses the production of elastomers by sulfochlorinating said copolymers having a molecular weight above 20,000 and preferably a molecular weight between 50,000 and 300,000, and then vulcanizing the sulfochlorinated products in the presence of metal oxides or similar vulcanizing agents.

The vulcanized products thus obtained have properties which are similar to the properties of elastic rubber. In particular, the vulcanizates obtained from the sulfochlorinated copolymers have a high elastic elongation coupled with excellent rebound.

We have found, in accordance with the present invention, that using particular operating conditions, the sulfochlorinated copolymers can be formed into elastic filaments and yarns which, after vulcanization, have mechanical properties comparable to those of the elastic yarns obtainable from natural rubber, and from certain synthetic rubbers, but which difier from the rubber filaments and yarns in having a much higher resistance to oxygen, ozone, ultraviolet light, and weathering.

Because of the last-mentioned characteristics of the present yarns they can be used for long periods of time without undergoing the changes to which the rubber yarns are susceptible, and without requiring the application of special protective coatings to them.

According to this invention, the sulfochlorinated copolymers are formed into yarns of various counts (which can be very low) by dissolving them in certain organic solvents and then spinning the solutions by the processes normally used for obtaining filaments from spinning solutions.

Certain selected solvents can be used in preparing the spinning solution. Useful solvents include benzene,

' stainless steel ball of 700 seconds from a height of 10 cm.

chloro-benzene, and carbon tetrachloride. The preferred spinning solutions are rather dilute, having a variable concentration between 2% and 20%, depending on the molecular weight of the ethylene-propylene copolymer.

In practice, the copolymers are generally sulfochlorinated in solution, e.g. in an inert solvent such as C(14- If desired, the dilute solution resulting from the sulfochlorination reaction can be used as the spinning solution, after the addition of suitable vulcanizing agents to it, such agents remaining with the filaments obtained, after re moval of the spinning solvent, and serving to facilitate curing of the filaments by subsequent heating.

For best results in the spinning step, it is advantageous to use a spinning solution having a viscosity comprised between definite and specific limits. We have found, empirically, that the simplest, most effective method for PbO 40%.

3,079,218 Patented Feb. 26, 1963 evaluating the viscosity which gives the best results under the given spinning conditions consists in determining the time required for a metallic sphere of given size to fall from a given height through the solution being tested. So determined, using a stainless steel sphere Weighing 0.1295 g. and a fall height of 10 cm., it has been found that the solutions give the best spinning results when the fall time is between 600 and 1200 seconds. Such solutions generally contain the sulfochlorinated copolymer in a concentration of 2% to 12%.

The solutions can be spun in accordance with usual dry-spinning techniques, by extruding them under pressure through the orifices of a spinneret into a dry-spinning cell in which the solvent is evaporated by means of hot air or other gaseous inert medium. The solutions can also be spun into a suitable coagulating bath in accordance with the wet-spinning method.

As coagulating bath, lower aliphatic alcohols, such as methanol, ethanol, iso-propanol etc., and lower aliphatic;

ketones, such as acetone, can be used.

Suitable apparatus for spinning the solutions is shown schematically in the accompanying drawing.

Referring to the drawing, there is shown a tank 1 from which the solution 2 is forwarded by means of the gear pump 3 to the'spinning head 4 and thence through spin-' The resulting vulcanized filaments and yarns formed therefrom have excellent elastic and mechanical properties which persist even after prolonged exposure of the filaments and yarns to weathering. The new filaments and yarns can be used for all'of the purposes for which rubber filaments and yarns are useful and have the advantages over the rubber articles which have been mentioned.

. The following example is given to illustrate the invention, it being understood that this example is not intended to be limiting.

EXAMPLE A linear ethylene-propylene copolymer containing 40% ethylene by weight in the copolymer molecule and having a molecular weight above 20,000 is sulfochlorinated in CCl to a sulfur content of 1.9% and a chlorine content of 7.8%. The resulting solution has a sulfochlorinated copolymer. concentration of 7%, and a fall time for the The following materials are added to the solution, the amounts shown being by weight percent on the sulfochlorinated copolymer:

Staybelite 2.5% .[a commercially available ethyleneglycol ester of hydro-' genated rosin].

Vulcafor HSS 0.25% (N-cyclohexyl-2- benzothiazol-sulfena mide).

The solution is spun into filaments by means of apparatus as shown in the drawing, using a cup-type spinneret having 18 orifices of 0.2 mm. diameter and provided with a 13,000-mesh/cm. net supported by two additional nets having 900 and 1500 -mesh/-c1n. respectively. The coagulating tank 5 has a length of 3 meters and contains methanol as the coagulating and setting bath.

After coagulation and drying, the filaments are vulcanized in an autoclave filled with live steam, at 145 C. for 30 minutes.

Table I below gives the characteristics of two lots of yarns formed from the vulcanized filaments and having slightly different counts. 7

Table II shows the results obtained when the yarns of the vulcanized filaments were tested for stability under ultraviolet light by exposing them, for the time indicated, to the light of a 100 watt quartz lamp placed in the focus of a parabolic mirror. The yarns were arranged in a horizontal plane, normally to the direction of the light and to the longitudinal axis of the mirror, at a distance of 30 cm. from the focus of the mirror. As is evident from Table II, the yarns retain their characteristics even after prolonged exposure to the ultraviolet light.

- Table III shows the data obtained when the yarns of the vulcanized filaments were tested for ageing characteristics in the presence of oxygen, using a Bierer-Davies apparatus which consists of a series of small autoclaves placed in a thermostat. The samples to be tested are hung from supports attached to the covers of the autoclaves. The test is carried out by keeping the samples in the presence of oxygen at 21 atm. and 70 C. for a given time. After the treatment with oxygen, the yarns are again tested to determine the tenacity, elongation and count thereof.

Table I I Count (total of the 18 filaments) denicrs 190 l 194 Tenacity, gJden 0.16 0.14 Elongation at break, A ercc 475 i 420 Permanent set (after stretching at 200%), percent. 2 2. Elastic modulus, g./den 0.018 0, 02

Table II Time, Hours 0 24 72 96 120 Total count in deniers 240 254 227 221 20s Tenacity, gJden 0.13 0.10 .07 0.07 0.06 Elongation at break, pcrccn 538 468 450 400 Table III Time, Hours f 0 72 230 190 235 200 0. 15 0. 13 0. l6 0. l4 Elongation, percent 520 430 510 I 440 It is apparent from the data listed in the tables, that the tensile strength of the vulcanized filaments formed from the sulfochlorinated ethylene-propylene copolymers is not altered as a result of the various treatments to which they are subjected during the tests. This is in sharp contrast to natural rubber filaments which, as is well known, undergo marked loss in'mechanical properties when exposed to the same treatments.

The ethylene-propylene copolymers which are sulfochlorinated to obtain the'presentstarting materials are obtainable by methods disclosed in the British Patent No. 856,736.

Briefly, as disclosed in said British patent, the copolymers are obtained by contacting a suitable mixture of ethylene and propylene in an inert hydrocarbon solvent with a catalyst prepared, by mixing an aluminum alkyl compound in which the alkyl groups contain up to 16 carbon atoms, with a hydrocarbon-soluble halide, oxyhalide or alkoxyhalide of a transition metal of Groups IV to VI of theMendeleeif Periodic Table, and particularly hydrocarbon-soluble compounds of vanadium. The ethylene and propylene to be copolymerized are used in a molar ratio in the gaseous phase which depends on the carbon content of the alkyl groups of the aluminum alkyl compound, and which molar ratio is at least 1:1 when said alkyl groupscontain 4 to 16 carbon atoms, and at least 6:1 when those groups contain less than 4 carbon atoms.

, spinning solvent.

The resulting copolymers containing from 5% to 70%, preferably from 30% to 70% of ethylene in the molecule are unique in that they are linear, head-to-tail amorphous under X-ray analysis, substantially free of homopolymcrs of either of the starting monomers, and have molecular weights above 20,000.

The linear, substantially amorphous and substantially pure copolymers can be sulfochlorinated according to the methods disclosed in the British Patent No. 861,542.

Briefly, as disclosed in said patent, one method for sulfochl rinating the copolymers is to dissolve them in a suitable solvent such as benzene or CCI and add to the solution C1 and an organic nitrogen-containing substance such as pyridine which promotes sulfochlorination in preference to chlorination. The sulfochlorinated copolymers can contain up to 10% of chlorine and from 0.2% to 3.0% of sulfur. However, chlorine atoms are much less active in the vulcanization than the SO CI groups. It is possible, under the conditions disclosed in said British Patent No. 861,542, to produce sulfochlorinated ethylene-propylene copolymers in which the amount of combined chlorine is from a few hundredths percent to less than 5%, e.g., from about 1.4% to about 4.5%, and in fact is limited to the amount corresponding to the SO Cl groups required for the vulcanization, i.e., substantially all of the chlorine combined with the copolymer is contained in the S0 01 groups.

Such sulfochlorinate-d linear, substantially amorphous ethylene-propylene copolymers containing less than 5% combined chlorine are preferred for use in the practice of the present invention.

Methods for vulcanizing the chlorosulfonated linear copolymers are also disclosed in said British Patent No. 861,542. Such methods involve heating the sulfochlorinated copolymers preferably in the presence of substances which are acceptors of the acidic byproducts formed during the heating. Suitable acceptors include metallic monoor polyvalent oxides such as lead oxide; monoor poly-primary, secondary or tertiary amines such as benzidine; alkali and alkaline earth metal salts of non-volatile weak organic or inorganic acids, etc.

The vulcanizing agents used are those commonly used in the'vulcanization of rubber. They can be added, in the usual small amounts, to the solution of the sulfochlorinated linear ethylene-propylene copolymer or they can be intimately mixed in any suitable device with the suitechlorinated copolymer before the latter is dissolved in the The vulcanizing agents remain distributed in the filaments on removal of the solvent and function to facilitate the curing during the subsequent heating to vulcanization temperature.

The filaments of the invention can be twisted together to form a yarn of desired count. They can also be col lected in the form of a filamentary tow which is forwarded to a zone in which the continuous filaments are disrupted to a mass of staple fibers suitable for blending with other synthetic fibers with natural fibers in any desired proportions. It is intended to include in the scope of the appended claims all such modifications and changes as may be apparent to those skilled in this art from the description of this invention as disclosed herein.

What is claimed is:

1. Elastic filaments and yarns of vulcanized sulfochlcrinated copolymers of ethylene and propylene containing, in the su'lfochlorinated state, from about 0.2% to about 3.0%. 01" combined sulfur and at least 1.4% but less than 10% of combined chlorine, the copolymers being characterized in that, prior to sulfochlorination, they are linear, amorphous under X-ray analysis, essentially free of homopolymers, contain from 5% to 70% by weight of ethylene in the copolymer molecule, show, in the infra-red spectrum therefor, bands between 13.4 microns and 13.8 microns, and have a molecular weight above 20,000.

7.. Elastic filaments of vulcanized sulfochlorinated copoiymers of ethylene and propylene containing, in the sulfochlorinated state, from about 0.2% to about 3.0% of combined sulfur and at least 1.4% but less than of combined chlorine, the copolymers being characterized in that, prior to sulfochlorination, they are linear, amorphous under X-ray analysis, essentially free of homopolymers, contain from 5% to 70% by weight of ethylene in the copolymer molecule, show, in the infra-red spectrum therefor, bands between 13.4 microns and 13.8 microns, and have a molecular weight above 20,000.

3. A process for obtaining elastic filaments and yarns characterized by high mechanical strength and resistance to weathering, which process comprises dissolving a sulfochlorinated linear copolymer of ethylene and propylene containing in the sulfochlorinated state from about 0.2% to about 3.0% of combined sulfur and at least 1.4% but less than 10% of combined chlorine, the copolymer being characterized in that, prior to sulfochlorination, it is amorphous under X-ray analysis, contains from about 5% to about 70% by weight of ethylene in the copolymer molecule, is essentially free from homopolyrners, shows, in the infra-red spectrum therefor, bands between 13.4 microns and 13.8 microns and has a molecular weight above 20,000, in a solvent for the copolymer selected from the group consisting of benzene, chlorobenzene, and carbon tetrachloride, to obtain a solution having a concentration of the sulfochlorinated copolymer of from 3% to 20% and a viscosity such that between 600 and 1200 seconds are required for a stainless steel sphere weighing 0.1295 gram to fall vertically through 10 centimeters of the solution, extruding the solution through a spinneret into a setting medium selected from the group consisting of lower aliphatic alcohols and lower aliphatic ketones to form filaments with removal of the solvent, and then vulcanizing the filaments by heating them at a temperature between 125 C. and 170 C. in the presence of at least one vulcanizing aid which is an acid acceptor selected from the group consisting of lead oxide, benzidine and N-cyclohexyl-Z-benzothiazol-sulfenamide.

4. The process according to claim 3, characterized in that the copolymer contains, in the sulfochlorinated state, at least 1.4% but less than 5% of combined chlorine.

5'. The process according to claim 3, characterized in that the copolymer contains from 30% to 70% of ethylene by weight in the copolymer molecule and is dissolved in benzene containing at least one of the vulcanizing aids.

6. The process according to claim 3, characterized in that the copolymer contains from 30% to 70% of ethylene by weight in the copolymer molecule and is dissolved in chlorobenzene containing at least one of the vulcanizing aids.

7. The process according to claim 3, characterized in that the copolymer contains from 30% to 70% by weight of ethylene in the copolymer molecule, and is dissolved in carbon tetrachloride containing at least one of the vulcanizing aids.

8. The process according to claim 3, characterized in that the copolymer contains from 30% to 70% of ethylene by weight, has a molecular weight of 50,000 to about 300,000, and, in the sulfochlorinated state, contains between 1% and 3% of sulfur and at least 1.4% but less than 5% of chlorine.

9. The process according to claim 3, characterized in that a solution of from about 2% to 12% of the sulfochlorinated copolymer in benzene is extruded through the spinneret.

10. The process according to claim 3, characterized in that a solution of from about 2% to 12% of the sulfochlorinated copolymer in chlorobenzene is extruded through the spinneret.

11. The process according to claim 3, characterized in that a solution of from about 2% to 12% of the sulfochlorinated copolymer in carbon tetrachloride is extruded through the spinneret.

12. A spinning solution consisting essentially of a sulfochlorinated copolymer of ethylene and propylene containing, in the sulfochlorinated state, from 0.2% to 3.0% of combined sulfur and at least 1.4% but less than 10% of combined chlorine, which copolymer is characterized in that, prior to sulfochlorination, it is linear, amorphous under X-ray analysis, essentially free of homopolymers, contains from 5% to of ethylene by weight in the copolymer molecule, shows, in the infrared spectrum therefor, bands between 13.4 microns and 13.8 microns, and has a molecular weight above 20,000, dissolved in a solvent therefor selected from the group consisting of benzene, chlorobenzene, and carbon tetrachloride and containing at least one vulcanizing aid selected from the group consisting of lead oxide, benzidine and N-cyclohexyl-Z-benzothiazol-sulfenamide, the solution having a copolymer concentration of 3% to 20% and a viscosity such that between 600 and 1200 seconds are required for a stainless steel sphere weighing 0.1295 gram to fall vertically through 10 centimeters of the solution.

13. A spinning solution according to claim 12, characterized in that the solvent is benzene.

14. A spinning solution according to claim 12, characterized in that the solvent is chlorobenzene.

15. A spinning solution according to claim 12, characterized in that the solvent is carbon tetrachloride.

16. A spinning solution according to claim 12, characterized in that the copolymer contains, in the sulfochlorinated state, at least 1.4% but less than 5% of combined chlorine.

References Cited in the file of this patent UNITED STATES PATENTS 2,404,714 Latham July 23, 1946 2,592,814 Ludlow Apr. 15, 1952 2,723,257 McAlevy Nov. 8, 1955 2,726,234 Field et al. Dec. 6, 1955 2,791,576 Field et a1. May 7, 1957 2,814,609 Borunsky Nov. 26, 1957 2,829,118 Wehr Apr. 1, 1958 2,879,261 Johnson et a1. Mar. 24, 1959 

1. ELASTIC FILAMENTS AND YEAR OF VULCANIZED SULFOCHLORINATED COPOLYMERS OF ETHYLENE AND PROPYLENE CONTAINING, IN THE SULFOCHLORINATED STAE, FROM ABOUT 0.2% TO ABOUT 3.0% OF COMBINED SULFUR AND AT LEAST 1.4% BUT LESS THAN 10% OF COMBINED CHLORINE, THE COPOLYMERS BEING CHARACTERIZED IN THAT, PRIOR TO SULFOCHLORINATION, THEY ARE LINEAR, AMORPHOUS UNDER X-RAY ANALYSIS, ESSENTIALLY FREE OF HOMOPOLYMERS, CONTAIN FROM 5% TO 70% BY WEIGHT OF ETHYLENE IN THE COPOLYMER MOLECULE, SHOW, IN THE INFRA-RED SPECTRUM THEREFOR, BANDS BETWEEN 13.4 MICRONS AND 13.8 MICRONS, AND HAVE A MOLECULAR WEIGHT ABOVE 20,000.
 3. A PROCESS FOR OBTAINING ELASTIC FILAMENTS AND YARNS CHARACTERIZED BY HIGH MECHANICAL STRENGHT AND RESISTANCE TO WEATHERING, WHICH PROCESS COMPRISES DISSOLVING A SULFOCHLORINATED LINEAR COPOLYMER OF ETHYLENE AND PROPYLENE CONTAINING IN THE SULFOCHLORINATED STATE FROM ABOUT 0.2% TO ABOUT 3.0% OF COMBINED SULFUR AND AT LEAST 1.4% BUT LESS THAN 10% OF COMBINED CHLORINE, THE COPOLYMER BEING CHARACTERIZED IN THAT, PRIOR TO SULFOCHLORINATION, IT IS AMORPHOUS UNDER X-RAY ANALYSIS, CONTAINS FROM ABOUT 5% TO ABOUT 70% BY WEIGHT OF ETHYLENE IN THE COPOLMER MOLECULE, IS ESSENTIALLY FREE FROM HOMOPOLYMERS, SHOWS, IN THE INFRA-RED SPECTRUM THEREFOR, BANDS BETWEEN 13.4 MICRONS AND 13.8 MICRONS AND HAS A MOLECULAR WEIGHT ABOVE 20,000, IN A SOLVENT FOR THE COPOLYMER SELECTED FROM THE GROUP CONSISTING OF BENZENE, CHLOROBENZENE, AND CARBON TETRACHLORIDE, TO OBTAIN A SOLUTION HAVING A CONCENTRATION OF THE SULFOCHLORINATED COPOLYMER OF FROM 3% TO 20% AND A VISCOSITY S!CH THAT BETWEEN 600 AND 1200 SECONDS ARE REQIRED FOR A STAINLESS STEEL SPHERE WEIGHING 0.1295 GRAM TO FALL VERTICALLY THROUGH 10 CENTIMETERS OF THE SOLUTION, EXTRUDING THE SOLUTION THROUGH A SPINNERET INTO A SETTING MEDIUM SELECTED FROM THE GROUP CONSISTING OF LOWER ALIPHATIC ALCOHOLS AND LOWER ALIPHATIC KETONES TO FORM FILAMENT WITH REMOVAL OF THE SOLVENT, AND THEN VULCANIZING THE FILAMENTS BY HEATING THEM AT A TEMPERATURE BETWEEN 125* C. AND 170* C. IN THE PRESENCE OF AT LEAST ONE VULCANIZING AID WHICH IS AN ACID ACCEPTOR SELECTED FROM THE GROUP CONSISTING OF LEAD OXIDE, BENZIDINE AND N-CYCLOHEXYL-2-BENZOTHIAZOL-SULFENAMIDE.
 12. A SPINNING SOLUTION CONSISTING ESSENTIALLY OF A SULFOCHLORINATED COPOLMER OF ETHYLENE AND PROPYLENE CONTAINING, IN THE SULFOCHLORINATED STATE, FROM 0.2% TO 3.0% OF COMBINED SULFUR AND AT LEAST 1.4% BUT LESS THAN 10% OF COMBINED CHLORINE, WHICH COPOLYMER IS CHARACTERIZED IN THAT, PRIOR TO SULFOCHLORINATION, IT IS LINEAR, AMORPHOUS UNDER X-RAY ANALYSIS, ESSENTIALLY FREE OF HOMOPOLYMERS, CONTAINS FROM 5% TO 70% OF ETHYLENE BY WEIGHT IN THE COPOLYMER MOLECULE, SHOWS, IN THE INFRARED SPECTRUM THEREFOR, BANDS BETWEEN 13.4 MICRONS AND 13.8 MICRONS, AND HAS A MOLECULAR WEIGHT ABOVE 20,000, DISSOLVED IN A SOLVENT THEREFOR SELECTED FROM THE GROUP CONSISTING OF BENZENE, CHLOROBENZENE, AND CARBON TETRACHLORIDE AND CONTAINING AT LEAST ONE VULCANIZING AID SELECTED FROM THE GROUP CONSISTING OF LEAD OXIDE, BENZIDINE AND N-CYCLOHEXYL-2-BENZOTHIAZOL-SULFENAMIDE, THE SOLUTION HAVING A COPOLYMER CONCENTRATION OF 3% TO 20% AND A VISCOSITY SUCH THAT BETWEEN 600 AND 1200 SECONDS ARE REQUIRED FOR A STAINLESS STEEL SPHERE WEIGHTING 0.1295 GRAM TO FALL VERTICALLY THROUGH 10 CENTIMETERS OF THE SOLUTION. 